The effect of low-dose external beam radiation on extraneural scarring after peripheral nerve surgery in rats

OBJECTIVE: Scar tissue is an inevitable result of peripheral nerve surgery. A variety of substances have been used to prevent epineurial scarring. In this study, the effect of low-dose radiation therapy on epineurial scarring was investigated. METHODS: Seventy-eight male Sprague-Dawley rats were studied. A total of 60 rats were subjected to one of three types of surgical procedure on the sciatic nerve, as follows: Procedure 1, external neurolysis (n = 20); Procedure 2, abrasive injury (n = 20); and Procedure 3, anastomosis (n = 20). On the left sciatic nerves, 700 cGy external beam radiation was administered 24 hours after surgery, and the right sciatic nerves served as a control group (surgery only). Eighteen animals without surgical intervention were used to establish the fibrotic effect of radiotherapy on normal nerves. A neurological examination was performed weekly. Six weeks after surgery, the extent of extraneural scarring was examined by gross microdissection by means of a numerical grading scheme and histological analysis. Cellular density and surface measurements of scar tissue were also evaluated. RESULTS: The dissection around the nerve was easier in rats treated with low-dose radiation compared with the control group. Furthermore, grading scores in both nerve adherence and nerve separability were significantly lower in treated nerves than in the control group (P less than or equal to 0.05). Low-dose radiotherapy decreased the scores of cellular density and surface measurement of scar tissue (P less than or equal to 0.05). In normal nerves, radio? therapy did not produce any fibrotic effects and the density of fibroblasts/fibrocytes was also very low. CONCLUSION: In the case of surgery or local trauma to peripheral nerve, the use of low-dose radiation therapy may be a safe method of limiting postoperative epineurial scar formation.